Perched above the Yoshino River in the Iya Valley in Tokushima Prefecture lies a small museum filled with monstrous secrets. The Yokai Yashiki, or Monster and Stone Museum, tells the history of the many monsters, demons, and spirits that inhabit the region. Yokai are a class of monster unique to Japanese folklore, and the museum is filled to the brim with them. Papier-mâché representations and artifacts line the walls, along with maps showing where in the surrounding remote landscape these yokai have been spotted. Objects supposedly previously owned by yokai are displayed neatly in glass cases, and you can even wander through a spooky, monster-filled tunnel to experience what it would be to stumble upon such creatures in the dark. You can have a nice photo-op with some kappa (an amphibious water demon) and read about the local Shigeru Mizuki, who has been certified to have actual yokai heritage.
Then, venture to the second floor, dedicated to the geography and geology of the region, along with samples of minerals found near and far. A video of how the valley, river, and mountains were formed millennia ago is projected above a detailed diorama of the province. There is a room dedicated to fluorescent gems and an exhibit on the famed Murchison meteorite, which fell in Australia in 1969.
When you are done with the museum, there is a great shop filled with local goods and produce, along with a few monster goodies and gemstone jewelry.